Uni-t UT523A Digital 2/3/4 Pole Earth Ground Resistance Megger Voltage Soil Resistivity Tester Meter RS232 Detailed UT523 Series Earth Resistance Soil Resistivity Tester is specially designed and manufactured for measuring earth resistance, soil resistivity, earth voltage, AC voltage. Adopting the latest digital and micro-processing technology, precise 4-pole, 3-pole and simple 2-pole method for earth resistance measurement, importing FFT and AFC technology, with a unique function of anti-interference capability and the ability to adapt to the environment, consistency of repeat testing, to ensure high precision, high stability and reliability for prolonged measure, which is widely used in electric power, telecommunications, meteorology, oil field, construction, lightning protection, industrial electrical equipment and other earth resistance, soil resistivity, earth voltage, AC voltage measurement. Parameter       Specification    Range    Best Accuracy        Model        UT523A        Earth Resisitance(R)    0.00-19.99    (2%+5)        20.0-199.9    (2%+5)        200-1999    (2%+5)        2.00k-19.99k    (2%+5)        20.0k-210.0k    (2%+5)        Soil Resistivity()    0.00m-99.99m    According to the precision of R(=2aR a:1 m-100m;=3.141)        100.0m-999.9m        1000m-9999m        10.00km-99.99km        100.0km-999.9km        1000km-9000km        AC Earth Voltage (V)    AC 0.00-750V    (2%+5)        Test Frequency    128Hz/111Hz/105Hz/94Hz(AFC)            Special Functions            Measuring Method    Earth Resistance: rated current change-pole method, measurement current 20mA Max            Soil Resistivity: 4-pole measurement (Wenner method)        Earth Voltage: average rectification(between P(S)-ES)        Short-circuit Test Current    AC 30mA max            Open-circuit Test Current    AC 40V max            Auto Range                Electrode Distance Range    Can be set 1m~200m            Test Voltage Wave    Sine Wave            Line Voltage    below AC 750V            Low Battery Indication    7.